Lung Lesions: Localization and Diagnosis-5

• Parenchyma refers to the functional tissue for gas exchange, including alveoli and interstitium.

Localizing Lung Lesions

• Right heart border is associated with the Right Middle Lobe (RML).
• Left heart border is associated with the Lingula Left Upper Lobe (LUL).
• Right hemidiaphragm is associated with the Right Lower Lobe (RLL).
• Left hemidiaphragm is associated with the Left Lower Lobe (LLL).
• Descending aorta is associated with the Left Lower Lobe (LLL).
• The silhouette sign appears when two structures have the same density, causing their border to be lost.
• Silhouette helps localize lesions in the lung.

Air Bronchogram Sign

• Air-filled bronchi become visible against a background of opaque, airless lung tissue.
• This indicates an abnormality in the alveoli.
• Seen in pneumonia, adenocarcinoma, and pulmonary edema.

Pneumonia: History and Physical (H&P) & Diagnosis

• Includes chills, malaise, loss of appetite, and myalgias.
• May include Tachypnea, Tachycardia, Fever with or without chills.
• Could have Decreased or bronchial breath sounds.
• Egophony and tactile fremitus, both suggest a consolidative process.
• Crackles on auscultation of the affected regions of the lung, Dullness on percussion
• Diagnosis includes History and Physical with Chest X-Ray PA & Lat (initial); CT; sputum or blood cultures (cultures = definitive for bact); strep test; Covid PCR (gold standard)

X-ray Patterns for Pneumonia

• Focal Airspace (consolidation) can cause a silhouette or an air bronchogram sign.
• It may involve part or all of a lobe of the lung.
• Focal Airspace is Usually caused by bacterial infection.
• Diffuse Interstitial (reticular) presents as an infection of the interstitium of the lung, usually bilateral, and often appears as multiple white lines.
• Diffuse Interstitial will have Perihilar, peribronchial thickening and mainly caused by viruses and mycoplasma (Covid PCR)
• Reticulonodular is a combination of reticular (net-like) and nodular (small, round) opacities.
• Reticulonodular will have Interstitial processes that spill into alveoli

Cases of Pneumonia

• Pneumococcal Pneumoniae (Strep Pneumo) includes fever and alternatively dry and productive cough for 5 days, with large consolidations in the right upper lobe and a bulging horizontal fissure, and right lower lobe.
• Fungal Pneumonia pt taking immunosuppressants after renal transplant and can also be a feature of Fungal Pneumonia.
• Features of Fungal Pneumonoa can also be Dense consolidation.
• Viral Pneumonia presents includes poorly defined nodules and reticular areas of increased opacity in both lungs, multifocal peribronchovascular or subpleural consolidation and ground-glass attenuation in both lungs, with some lesions have a lobular distribution.
• Fungal Pneumonia is the most common opportunistic and life-threatening pulm infection in AIDS.
• Radiographic changes for Fungal Pneumonia are varied and may lag behind the symptoms
• A classic appearance of Fungal Pneumonia appears as bilateral symmetric perihilar or diffuse interstitial opacification, which may be reticular, finely granular or ground-glass in appearance.
• If left untreated, Fungal Pneumonia may progress to alveolar consolidation in 3 or 4 days.

Atelectasis

• Involves loss of volume or collapse of the affected area and the affected lung tissue is WHITE.
• There are three main causes of Atelectasis: obstruction, compression and traction.
• Health and Physical findings can be asymptomatic or show shortness of breath, increased respiratory rate, and cyanosis with decreased breath sounds, crackles, and reduced chest expansion.
• Diagnosis can be made using Chest X-Ray, CT, or bronchoscopy.
• Collapse of each lobe has its own characteristic appearance on the chest radiograph.
• Ipsilateral deviation, tenting of diaphragm, increased density occur with Atelectasis
• Overinflation of opposite side, may see on lateral view at diaphragm.
• The silhouette sign is a feature of Atelectasis.

Emphysema

• Emphysema destroys alveoli and results in obstruction of small airways leading to air trapping - increased lung volumes.
• H&P-smoking, SOB, chronic cough, ↑ AP diam(Barrel chest)
• hyperinflated diagnosis can involve flattened diaphragms, Diminished vascular markings and even include Vertical heart.
• Bulla or Blebs can lead to spontaneous pneumothorax in Emphysema.

Lung Neoplasms

• Nodule/Mass appear as round white fluid density lesions and can be malignant or benign.
• If less than 3cm = nodule, if greater than 3cm = mass
• Screening/Survaillance include CXR (compare to baseline CXR), CT without contrast.
• Work-up hemoptysis should include Chest CT with contrast.
• If contrast is contraindicated, then chest CT should be ordered without contrast.
• Can confirm Lung Neoplasms with transthoracic needle biopsy or PET/CT
• Staging: Chest CT with or without contrast if renal failure or PET/CT
• The snowball sign (Extra-pleural sign) is used to determine if a peripheral mass or nodule arises from the lung or from a surrounding structure.
• If the mass or nodule looks like a snowball just before impact, it is LOCALIZED in the lung.
• If the mass or nodule looks like a flattened snowball just after impact, it arises from a surrounding structure (chest wall, pleural, or mediastinum).
• Benign lesions tend to be small, well defined, smooth, round and maybe calcified, usually stable in size over time.
• Hamartoma (benign) is a mixture of cartilage and smooth muscle.
• Adenocarcinoma is not benign and the most common cancer in the lung(smokers and nonsmokers)
• Primary lung cancers tend to have ill-defined, spiculated borders and grow over time, with mets producing multiple smooth round lung nodules often variable in size.
• Lymphoma can cause Thin-walled cavities

Pleural Effusion/Hemothorax/Empyema

• Pleural Effusion/Hemothorax/Empyema is the Collection of fluid between the visceral pleural and the parietal pleural.
• This fluid may be serous (pleural effusion), blood (hemothorax) or pus (empyema)
• H&P findings include pleuritic pain that worsens with breathing), SOB, cough, fever, chills, and hiccups
• Diagnosis can be made using Xray finding white opacities, meniscal line obliteration of diaphragm
• PA findings for Pleural Effusion/Hemothorax/Empyema include white opacities and the meniscal line ob alteration of diaphragm
• Lateral findings for Pleural Effusion/Hemothorax/Empyema include Fluid, and it will accumulate on the bottom.

Tension pneumothorax

• Involves air between the parietal and visceral pleura,usually from a lung injury.
• History of sudden, sharp chest pain, shortness of breath, and potentially diminished or absent breath sounds on the affected side.

Radiographic Features for Tension pneumothorax

• includes the visceral pleural which is seen as a thin white line under the black crescent, loss of blood vessels peripheral to this line.
• X-ray shows complete opacification of the right hemithorax.
• X-ray shows shifted heart and mediastinal structures, toward the right inidcating volume loss.
• The right 5th rib is surgically absent. Surgical clips will also be seen.